<?php
namespace app\models;

use Yii;
class captcha{
    /**
     * 使用实例化方法
     */
    public static function index(){
        $session = Yii::$app->session;
        header ('Content-Type: image/png');

        $image=imagecreatetruecolor(100, 30);
//背景颜色为白色
        $color=imagecolorallocate($image, 255, 255, 255);
        imagefill($image, 20, 20, $color);

        $code='';
        for($i=0;$i<4;$i++){
            $fontSize=8;
            $x=rand(5,10)+$i*100/4;
            $y=rand(5, 15);
            // $data='abcdefghijklmnpqrstuvwxyz123456789';
            $data='ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789';
            $string=substr($data,rand(0, strlen($data)),1);
            $code.=$string;
            $color=imagecolorallocate($image,rand(0,120), rand(0,120), rand(0,120));
            imagestring($image, $fontSize, $x, $y, $string, $color);
        }
        $session['code']=$code;//存储在session里

        for($i=0;$i<200;$i++){
            $pointColor=imagecolorallocate($image, rand(100, 255), rand(100, 255), rand(100, 255));
            imagesetpixel($image, rand(0, 100), rand(0, 30), $pointColor);
        }
        for($i=0;$i<2;$i++){
            $linePoint=imagecolorallocate($image, rand(150, 255), rand(150, 255), rand(150, 255));
            imageline($image, rand(10, 50), rand(10, 20), rand(80,90), rand(15, 25), $linePoint);
        }
        imagepng($image);
        imagedestroy($image);
    }
}
